The present invention relates to battery chargers.
Recent years have seen a proliferation of battery powered electrical devices. Digital cameras, personal digital assistants (PDAs), hand held games, portable audio players, remote control devices, wireless computer keyboards and mice, and mobile telephones are but a few examples of this trend.
Rechargeable (secondary) batteries, such as nickel-metal hydride (NiMH), nickel-cadmium (NiCd), and lithium ion (LiIon) electrical cells, have likewise gained increasing acceptance as a renewable power source for these and other devices. Rechargeable batteries are typically well-suited for use in relatively high-drain devices, making them attractive in a wide variety of applications. As they can be recharged and reused, rechargeable batteries can also provide convenience and cost advantages relative to non-rechargeable (primary) batteries.
One factor which affects the utility of rechargeable batteries and the chargers needed to charge them is increasing mobility. As but one example, business travelers often require the use of a battery powered appliance while on a business trip. As another, a leisure traveler may likewise wish to use a digital camera while on a trip or outing. In either case, the user may wish to have a supply of replacement batteries ready to hand.
Functionality can also be a factor in less mobile situations. For example, a user may wish to charge a number of batteries, whether for immediate use or use at a later time. Once the batteries are removed from the charger, however, the batteries sometimes become misplaced or otherwise disorganized.
Factors such as size, ease of use, and charging time can also influence the decision to use to a particular charger. In situations where a user wishes to charge multiple batches of batteries, it is generally desirable that the batches are charged as quickly as possible, or otherwise in an easily understood and predictable way. It is also desirable that the available charging capacity be used relatively efficiently, and that the charging of the various batteries in a batch be completed at about the same time.